环状共聚物的电子特性研究

Electronic properties of ring copolymers

针对由小带隙的聚乙炔和大带隙的苯作为聚合物单体的聚合物的几种简单环状模型,采用紧束缚近似计算方法,研究了它们的电子能谱和态密度特征,并考虑到环状结构的特点,同时在计算过程中也考虑了聚乙炔链中的最近邻和次近邻跃迁.结果表明:由于考虑了次近邻跃迁,导带和价带的对称性被破坏了,有着明显的不对称特征,能隙稍变窄.随着环状聚乙炔链中的苯环数的增多,电子能谱和态密度均有显著的变化,能谱分布逐渐不均匀,呈现出较明显的4条能带,态密度分布也相应地出现4个峰.

The electronic energy spectrum and density of states (DOS) for several simple ring copolymers have been studied by using a tight-binding calculation. The ring copolymers are composed of homopolymer (-(PA)_X-) and benzene.Considering of the ring structure, the non-nearest-neighbor hopping in a trans-polyacetylene chain was taken into account. The results showed that the non-nearest-neighbor hopping not only broks the symmetry of the energy band but also narrowed the band gap, and four energy bands were formed with increasing the number of benzenes in the copolymer.